The host's inflammatory response to the infection, through the release of proteolytic enzymes and IL-1, is primarily responsible for the destructive cartilage changes seen in septic arthritis. Injury to the cartilage may occur within 8 hours, so prompt diagnosis and treatment is crucial for joint preservation.

Clinical Presentation

Pain is an essential component of the constellation of symptoms associated with septic arthritis of the elbow. It may be described as a deep, poorly-localized pain within the elbow, often acutely exacerbated by attempted range of motion. Septic arthritis can also manifest as an inability to bear weight on the affected upper extremity. Fevers may accompany septic arthritis, indicating a systemic source or spread. The patient may appear toxic, especially in more advanced stages of the infection.

Diagnostic Workup

On physical examination, the affected elbow will often appear warm, erythematous, and tender to palpation. An overlying cellulitis or abscess may be present and should be noted. Swelling about the elbow with a concomitant joint effusion are seen. Flexion and extension of the elbow, and perhaps supination-pronation, will be limited secondary to extreme pain.

Imaging Workup:

Radiographs: AP, lateral, and oblique views of the elbow should be obtained. These may demonstrate joint space widening or effusion. Anterior and/or posterior (more sensitive for inflammation) fat pad signs may be evident.

Ultrasound: Although not routinely utilized, ultrasound may help guide joint aspiration and confirm an effusion.

ESR: Rises after 2 days of infection, normalizes 3 - 4 weeks after the initiation of appropriate treatment.

CRP: Rises within hours after infection, normalizes after 1 week. CRP is the more sensitive indicator.

Elbow Joint Aspiration:

The gold standard for diagnosing joint infection. Aspirate should be sent for WBC count with differential, gram stain, culture (aerobic and anaerobic), crystal analysis, and acid-fast staining.

Findings: Aspirate is purulent or cloudy. WBC > 50,000 - 80,000, PMNs > 75% in a native elbow. In the setting of an elbow prosthesis, WBC > 1,100, PMNs > 65% suggestive of an infection. Be sure to check crystal results to assess for gout (monosodium urate) and pseudogout (calcium pyrophosphate), as gouty attacks present similarly to a septic joint.

Aspiration Technique: Access to the elbow is achieved through a lateral approach.

1. Place patient supine with elbow at 45 degrees of flexion and hand in neutral position.

2. Prep skin along lateral aspect of elbow with alcohol and povidone-iodine.

3. Using a 20-gauge needle with a 5 - 10 mL syringe, penetrate the region of the elbow in the middle of a triangle formed by the lateral epicondyle (proximally), radial head (distally), and olecranon process (posteriorly).

Non-Operative Management

Non-operative treatment alone for septic arthritis of the elbow is rarely indicated as the sequelae, such as destruction of the joint and progressive osteomyelitis, can lead to significant pain and functional deficits. Reserved for patients with substantial co-morbidities that preclude an operative intervention. Entails the administration of intravenous antibiotics. Empiric antibiotics should be initiated immediately after joint aspiration, with the patient ultimately transitioned to pathogen-specific antibiotics based upon culture and sensitivity results from the aspirate. The duration of antibiotic therapy is typically 2 - 6 weeks. (See Table II)

Indications for Surgery

Given its destructive nature, septic arthritis of the elbow is considered an orthopaedic emergency and should be managed surgically. Options include open or arthroscopic irrigation and debridement of the elbow. In the setting of an infected elbow replacement, consideration should be made towards removal of the prosthesis with placement of an antibiotic spacer. Following surgery, antibiotic therapy should proceed as outlined in "Non-Operative Management."

Surgical Technique

Open Irrigation and Debridement

An anterolateral approach to the elbow is typically performed. The intermuscular plane is between the brachialis and brachioradialis (proximally) and the pronator teres and brachioradialis (distally).

3. Gravity exsanguinate the limb, inflate tourniquet, and then insufflate elbow joint with 20 - 30 mL of saline through the lateral elbow (same site as described for aspiration in "Diagnostic Workup").

9. Establish posterolateral portal for the arthroscope 3 cm proximal to the tip of the olecranon.

10. Create direct posterior portal for shaver also 3 cm proximal to the tip of the olecranon but medial to the posterolateral portal.

11. Debride posterior aspect of elbow joint.

12. Close portal sites.

Pearls and Pitfalls of Techniques

Pearls

For open procedures, ligate the recurrent branches of the radial artery and branches to the brachialis below the elbow to permit improved retraction.

For arthroscopic procedures, insufflate the joint to facilitate distention for safe entry of instruments.

Assess the stability of the ulnar nerve prior to making medial portals. Subluxation increases risk of injury.

Pitfalls

Do not forget to obtain intra-operative fluid and tissue cultures. While antibiotic therapy may have already been initiated by the time of surgery, which could obscure cultures, the results can be highly valuable in guiding treatment.

Post-operative Rehabilitation

Patient may be placed in a long-arm posterior slab splint for post-operative comfort. Initiate passive and active range of motion of the elbow (flexion, extension, supination, pronation) with weight-bearing as tolerated promptly to avoid stiffness. After irrigation and debridement with initiation of antibiotics, monitor WBC count, ESR, and CRP levels to assess the response to therapy.

(In this small series, maximum outcome scores were achieved when arthroscopy was performed within 2 days after the onset of symptoms. Note: "OES" refers to "Oxford Elbow Score" and "MES"denotes "Mayo Elbow Score.)

Summary

Septic arthritis of the elbow can be caused by a variety of pathogens, most commonly S. aureus. Given the potential for cartilage degradation and joint destruction, a septic elbow is considered an orthopaedic emergency requiring prompt diagnosis and treatment. Elbow joint aspiration and fluid analysis is the gold standard for diagnosis. Surgical options include open or arthroscopic irrigation and debridement of the joint. Appropriate intravenous antibiotic therapy should be promptly initiated and tailored to cultures obtained from joint aspiration and surgery. An infectious disease specialist should be consulted.